Prof Matthew Thirlwall, Royal Holloway

The Late Caledonian Igneous Province: can we distinguish origins via subduction or slab failure?

The origin of the abundant igneous activity in Scotland, that postdates the Grampian Orogeny and is broadly associated with Old Red Sandstone sediments, has been debated extensively since the 1980s. Recently published interpretations have focussed on slab failure as a mechanism for magma generation. This talk looks critically at some of the evidence used to support this origin, particularly geochronological and geochemical evidence. I show that the age, location and chemistry of magmas north of the Southern Uplands are consistent with an origin through active subduction, and that much of the evidence used to infer a slab failure origin is ambiguous.

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